Download Module 3 – Chemical Patterns

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Module 1a – Biology – Human biology
You should know about the following four areas:
1
Co-ordination and control
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The nervous system and the hormone system co-ordinate your body
The input to the nervous system is by the sense organs which detect stimuli
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Stimuli are changes in your environment
The sense organs are the ears, nose, tongue, eyes and skin
Remember that the ears detect balance/movement as well as sound
The tongue and nose both detect chemical stimuli
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The brain and the spinal cord make up your Central Nervous System (CNS)
This is where all your sensory input and responses are co-ordinated
The sensory neurones carry the input impulses
The motor neurones carry impulses which make you respond
A neurone is another name for a nerve cell
The impulses are electrical signals that carry information to/from the CNS
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Some stimuli produce an automatic response
We call these reflexes. The pathway of the neurones is a reflex arc
Reflexes are very fast. They often protect us.
The path of a reflex is:
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Hormones also co-ordinate the body’s responses
They are special chemicals secreted by glands in different parts of the body
The hormones travel all round the body in the blood plasma
Each hormone affects certain target cells which may be a long way away from the gland
Eg
Stimulus – receptor – sensory neurone – relay neurone – motor neurone – effector – response
Many reflexes don’t go through the brain but just pass through the spinal cord
An effector may be a muscle or a gland
Hormone gland
pancreas
testes
Hormone made/secreted
insulin
testosterone
What it does
Controls blood sugar levels
Changes the body at puberty
http://www.bbc.co.uk/schools/
gcsebitesize/science/aqa/
is a good site for revision
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More about co-ordination and control….
In women, the menstrual cycle is controlled by hormones. It lasts about 28 days
Day 1 – 5 is the menstrual period; ovulation happens around day 14.
The hormones are produced by the ovaries and the pituitary gland (under the brain)
Hormone
Where it’s
Where it acts
What it does
made
FSH
pituitary
ovary
Makes an egg mature
Makes the ovary secrete oestrogen
Oestrogen
ovary
pituitary
Inhibits FSH production
Stimulates LH production
LH
pituitary
ovary
Causes ovulation (egg release)
These hormones can also be used to control fertility, to stop pregnancy or make it more
likely
The Contraceptive pill (oral contraceptive) reduces fertility
It contains oestrogen which inhibits FSH production. This means that eggs are not
produced. With no eggs the woman can not get pregnant
You need to be able to weigh up the advantages and disadvantages of this
contraceptive method
Advantages of oral contraceptives
Disadvantages of oral contraceptives
Doesn’t protect against sexually transmitted infections
Over 99% effective
Helps prevent painful periods
It isn’t 100% effective
Protects against some cancers
There may be side effects, eg weight gain
 ‘Fertility drugs’ are used to help women who don’t make many eggs
 This is called IVF or In Vitro Fertilisation
 The drugs contain FSH. FSH stimulates the ovaries to make more eggs
 The advantage is that the woman may have a baby
 The disadvantage is that it is very expensive and doesn’t always work
 Our cells are very easily damaged. They have to have a constant environment where
temperature, water content, ion concentrations and blood sugar levels are all tightly
controlled
 Homeostasis means controlling the internal environment
Factor controlled
Ion content
Water content
Temperature
Blood sugar level
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How it is done
The kidneys excrete excess ions in the urine
The kidneys excrete excess water in the urine
The brain monitors the core temperature and keeps it at 37oC
Too hot? We sweat and lose heat
Too cold? We shiver which warms us
The pancreas secretes a hormone (insulin) which lowers blood
glucose levels. If we can’t make insulin we get diabetes
Manufacturers often make claims about their products, eg sports drinks
You need to evaluate these claims: are they true or not? What’s the evidence?
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9
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Healthy eating
Our diet is the food and drink we take in. A healthy diet will give us the
right amount of each nutrient and energy.
Too much or too little food or the wrong food may make us malnourished.
This could make us fat or thin or we could get a deficiency disease
We all need proteins for growth & repair;
fats and carbohydrates for energy
vitamins and minerals to keep us healthy
fibre to move food through our gut
 Our metabolic rate is the speed at which our body does chemical
reactions. It is linked to how much exercise we take and to how
much muscle and fat we have. Our metabolic rate stays high for
a while after exercise. The more regular exercise we do, the
fitter we are.
 The less exercise we take, the less food we need.
weight problems - weight problems – weight problems – weight problems – weight problems
 Too much food? Too little exercise? – may cause obesity and other diseases
 Arthritis, diabetes, high blood pressure and heart disease are all linked to being too fat
Too little food? Not enough nutrients? This is common in the developing world and may
cause reduced resistance to infection and irregular periods in women
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Cholesterol
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Is made in the liver and found in the blood
Is bad for the heart and blood vessels if levels are too high
Is carried round the body in lipoproteins:
High density lipoproteins (HDLs) are ‘good’ and reduce the risk of heart disease
Low density lipoproteins (LDLs) are ‘bad’ and can cause heart disease
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Saturated fat increases blood cholesterol levels
Mono-unsaturated fats and polyunsaturated fats may help to reduce
cholesterol levels
In some people, too much salt may increase the risk of high blood pressure
Fast food ( processed food) often contains high levels of fat and salt
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The RSS sections on
http://www.bbc.co.uk/schools/gcsebitesize
/science/aqa/ are very useful
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12
Drug abuse!
Some drugs can be good for you but
others harm the body.
Indigenous people have known about
drugs from plants for many years
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A drug is something that changes the body’s chemical
processes
Dependent people are addicted to drugs. They suffer
withdrawal symptoms without their drugs
Heroin and cocaine are very addictive
Many people use recreational drugs. Some are legal, others are illegal.
Legal drugs such as alcohol and tobacco cause
Why is
more health problems overall than illegal drugs.
this?
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Alcohol affects the nervous system. It slows reactions and helps people
relax.
Too much can lead to lack of self-control, unconsciousness, even coma.
It can also damage the brain and liver.
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Tobacco smoke contains many dangerous substances
Nicotine is the addictive substance in tobacco smoke
Carcinogens in tobacco smoke may cause cancer of different organs
The link between smoking and lung cancer has been agreed over many years
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Carbon monoxide in tobacco smoke makes the blood carry less oxygen
This is dangerous in preganant women as the foetus may not get enough oxygen.
It may have a low birth mass
Many smokers try to quit. There are many different ways to do this
Cannabis is illegal in many countries but smoked by millions of people round the world
There are many claims about cannabis:
Some people say it helps treat disease symptoms such as chronic pain
Insert
Others say that smoking cannabis may lead to mental illness
cannabis
Some cannabis users go on to use hard drugs and to become addicted
leaf pic
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Controlling Infectious Disease
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Micro-organisms that cause infectious disease are called pathogens
The main kinds are bacteria and viruses
Bacteria are very small cells with no nucleus.
Their DNA is free in the cytoplasm
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Bacteria and viruses may reproduce rapidly inside the body
They may make poisons (toxins) which make us feel ill.
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Viruses are much much smaller than bacteria; they are not cells
They are just a protein coat around some genetic material
Viruses reproduce inside our cells and damage them.
Semmelweiss investigated infectious disease in hospitals
He found out how to control infection
He told doctors to wash their hands
Many of his ideas are still important today
Insert
bacteria
& virus
pics
Can you evaluate
his work?
The body can protect itself against many pathogens
Our natural defence mechanisms include white blood cells which
Ingest (‘eat’ ) pathogens
Produce antibodies which kill particular pathogens
Produce antitoxins which counteract the toxins made by some pathogens
(different white blood cells do different jobs)
We can use drugs (medicines) to relieve the symptoms of some diseases.
These do not kill the pathogens
Painkillers work like this
Antibiotics (eg penicillin) kill bacteria inside the body
Antibiotics can’t kill viruses which live and reproduce inside our cells
It is hard to kill viruses without killing our own cells
Many bacteria have developed resistance to antibiotics.
This happens when some bacteria mutate to become resistant
The resistant bacteria survive and become more common when an antibiotic is used
This is called natural selection (the best-adapted organisms survive & pass on their genes)
MRSA is an example of an antibiotic – resistant bacterium
We must avoid over-use of antibiotics to stop more bacteria becoming resistant
Some mutations make animal or bird pathogens become dangerous to humans
New diseases may affect humans (eg bird flu)
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22.
More about Controlling Infectious Disease
1. New drugs
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It costs a lot of money to develop new drugs
They must be tested and trialled for many months
First they are tested in the laboratory to see if they are toxic
Then they are trialled on human patients and checked for side effects
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Thalidomide was developed as a sleeping pill
It also stopped pregnant women suffering from morning sickness
It was given to many pregnant women but it had not been tested on pregnant women
Many women gave birth to babies with severe limb abnormalities
The drug was banned
Recently Thalidomide has been used successfully to treat leprosy
23.
More about Controlling Infectious Disease
2. Immunity
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When a pathogen gets into our body, white blood cells produce antibodies that kill it
If that pathogen gets in again, we can respond rapidly (fast) and make the correct
antibody We do not get ill from that pathogen again. We are immune to it.
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Some pathogens are so dangerous that they may kill us before we kill them
We can immunise people against some of these dangerous pathogens
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Some dead or weakened pathogen is introduced into the body
(vaccination)
The white blood cells produce antibodies that destroy this
pathogen
Now the body can respond quickly if the live pathogen gets in again
in the future and we are immune to this pathogen
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Measles, Mumps and Rubella are dangerous diseases that can kill.
Most babies have the MMR vaccination to make them immune to these diseases
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Some diseases no longer happen because of the vaccination programmes all over the world
Smallpox is not found anywhere in the world
http://www.timetabler.com/physics4u
/4Ufreepowerpoints.html has some
great stuff on How Science Works
(variables etc etc)
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Derryclare
We love biology! SO LEARN THIS WELL!!!